1. Field of the Invention
This invention relates to a folding machine for a rotary press, and more particularly relates to a folding machine with a collect run mode capable of folding in such a manner as to be capable of selectively switching over between straight folding and collect folding when folding a paper web printed on using a printing unit using a folding cylinder and a jaw cylinder parallel to the axes of these cylinders after cutting the paper web.
2. Description of the Related Art
Conventionally, with folding machines for rotary presses, folding machines provided with operating functions for switching between straight folding and collect folding such as technology (prior art 1) disclosed in Japanese Patent Application Laid-open No. Hei. 7-157192 and the technology (prior art 2) disclosed in Japanese Patent Publication No. Sho. 56-018500 are well known.
The folding machines disclosed in prior arts 1 and 2 have formers and folding cylinders. This group of folding cylinders comprises a cutting cylinder having a cutting knife for cutting the paper web folded by the former to a prescribed length, pins for releasing the cut paper at an appropriate timing after sequentially holding the leading part of the cut paper sequentially at peripheral surfaces of the cylinders, a folding cylinder having a folding blade provided with a tip projecting slightly from the cylinder surface so as to cause a central part of the cut paper held at the cylinder surface to project in a direction parallel to the axial direction of the cylinder, and a jaw cylinder provided facing the folding blade provided at the folding cylinder surface, equipped with a jaw mechanism for holding the central part of the cut paper projected by the folding blade and folding this in a direction parallel to the axis of the cylinder.
With the straight folding by the folding machine disclosed in prior arts 1 and 2, after forming papers cut for each pattern from a paper web on which the same pattern has been printed consecutively by a printing unit, the papers cut with the same pattern are sequentially held at the surface of the folding cylinder, and each item of cut paper held is held by the jaw mechanism of the jaw cylinder and folded to give a signature.
More specifically, each of the pins of the folding cylinder is pulled in to within the folding cylinder one time during one revolution of the folding cylinder and the cut paper at the surface of the folding cylinder is passed over from the folding cylinder to the jaw cylinder so as to give a signature once for every 1/M revolutions of the folding cylinder (where M is the number pieces of cut paper it is possible to hold at the surface of the folding cylinder).
With collect folding using the folding machines disclosed in prior arts 1 and 2, cut paper is formed for each pattern from a paper web printed consecutively back and forth with two different patterns using a printing unit. This cut paper with differing patterns is then sequentially held at the surface of the folding cylinder, the folding cylinder is rotated one time, and at a position where the cut paper is held by pins, a new cut paper with a different pattern is overlaid and held, with each cut paper then being held by the jaw mechanism of the jaw cylinder and folded to give a signature in the same way as for during straight folding.
More specifically, as it is possible to overlay cut paper with different patterns on the folding cylinder surface, the number of pieces of cut paper M it is possible to hold at the surface of the folding cylinder, i.e. the number M of pins and folding blades, is taken to be an odd number, each of the pins of the folding cylinder is pulled into the folding cylinder one time during two revolutions of the folding cylinder and the cut paper on the folding drum surface is passed from the folding cylinder to the jaw cylinder one time for every 2/M revolutions of the folding cylinder (where M is the number of pieces of cut paper it is possible to hold at the surface of the folding cylinder).
Next, a detailed description is given of the folding mechanism disclosed in prior art 1. The folding machine of prior art 1 is alternately provided with odd-numbered rows (three or five) of pins and odd-numbered rows (three or five) of folding blades in a circumferential direction of the cylinder surface. When the folding cylinder rotates, a cam follower coupling with the pins is guided, and the fixed cam for moving the pins forwards or backwards from the surface of the cylinder is fixed to the side of the frame.
The cam profile of the fixed cam 1 comprises a circular peripheral part causing the pins to advance projecting from the surface of the folding cylinder and a recess part causing the pins to retract and be drawn in from the surface of the cylinder. At the recess part of the fixed cam, the pins release held cut paper from the cylinder surface by being retracted and enable delivery of the cut paper to cylinders downstream. The fixed cam has a recess at the prescribed position for carrying out a straight run.
A rotating cam is provided rotating at a position next to the fixed cam with a predetermined prescribed rotational speed ratio with respect to the rotation of the folding cylinder in accompaniment with the rotation of the folding cylinder.
The rotational cam is partially provided with partial covering sections of the same outer diameter as the outer diameter of the circular peripheral surface part of the fixed cam so as to enable covering of the recess part of the fixed cam, with other outer peripheral surface portions having a smaller diameter than the outer diameter of the circular peripheral surface part of the fixed cam and constituting non-covering sections that do not cover the recess part of the fixed cam.
Further, a rotating cam is disclosed where the rotating cam has covering sections at two symmetrical portions, and the other outer surface portions are taken to be non-covering sections.
The rotating cam rotates at a predetermined prescribed rotational speed ratio with respect to the rotation of the folding cylinder in accompaniment with the rotation of folding cylinder and it is possible for a large diameter part of the rotating cam to cover a small diameter part of the fixed cam. As a result, the pins hold two pieces of cut paper at the surface of the folding cylinder. This is then delivered to the jaw mechanism of the jaw cylinder so as to give a mechanism that folds by carrying out collect folding. Folding blades provided at the folding cylinder are fixed to the folding cylinder body and do not perform an operation of advancing and retreating from the surface of the folding cylinder.
Further, an even number of rows of jaw mechanisms (six rows) are provided at the jaw cylinder in the circumferential direction of the jaw cylinder. Moreover, although this is not described in detail, all of the jaw mechanisms operate during straight run, while the jaw mechanisms operate every other row, i.e. just a predetermined number of three rows of the six rows operate at the same time during collect folding.
Next, a detailed description is given of the folding machine disclosed in prior art 2. The folding machine of prior art 2 is alternately provided with odd-numbered rows (three) of pins and odd-numbered rows (three) of folding blades at the folding cylinder in a circumferential direction of the cylinder surface, and also provided with two cams fixed and spaced with respect to each other at the frame side, a cam guiding a cam follower coupled with pins in accompaniment with the rotation of the cylinder, the other cam guiding a cam follower coupled with the folding blade to cause the folding blade to advance or retract from the surface of the folding cylinder.
The cam profile of the fixed cam guiding the cam follower coupling with the pins comprises a large diameter section causing the pins to advance and project from the surface of the folding cylinder and a small diameter section causing the pins to retract to withdraw from the surface of the folding cylinder. The cam profile of the fixed cam guiding the cam follower coupling with the folding blade comprises a small diameter section causing the folding blade to advance and project from the surface of the folding cylinder and a large diameter section causing the folding blade to retract to withdraw from the surface of the folding cylinder.
At the small diameter section of the fixed cam for the pins, the pins retract from the cylinder surface to release the held cut paper, while at the small diameter at the fixed cam of the folding blade, the folding blade projects from the surface of the cylinder to cause a central part of the cut paper to project at the jaw mechanism of the jaw cylinder facing the folding blade, and the cut paper is delivered to a downstream jaw cylinder. The fixed cam is a shape for carrying out straight run, i.e. the prescribed position is the small diameter section.
Further, a rotating cam for the pins and a rotating cam for the folding blades rotating in accompaniment with rotation of the folding cylinder are provided between the fixed cam for the pins and the fixed cam for the folding blades. The two rotating cams are next to each other with a gap therebetween and are provided so as to be capable of being rotated in an integral manner.
These rotating cams comprise a rotating cam for the pins positioned at the side of the fixed cam for the pins and of a shape such that it is possible for the large diameter section of the rotating cam to shield the small diameter section of the fixed cam for the pins and a rotating cam for the folding blade positioned at the side of the fixed cam of the folding blade and of a shape such that it is possible for the large diameter section of the rotating cam to shield the small diameter section of the fixed cam of the folding blade.
The rotating cam rotates at a predetermined prescribed rotational speed ratio with respect to the rotation of the folding cylinder in accompaniment with the rotation of folding cylinder and it is possible for the large diameter section of the rotating cam to individually block the small diameter section of the fixed cam for the folding blade. As a result, the pins hold two pieces of cut paper overlaid at the surface of the jaw mechanism of the jaw cylinder so as to give a mechanism that folds by carrying out collect folding.
The jaw cylinder is such that jaw mechanisms composed of an odd number of rows (three) of jaw blades and jaw anvils are provided at equally spaced positions about the circumferential direction of the jaw cylinder. Further, a cam is provided by being fixed to the frame side for guiding a cam follower coupled with the jaw blade in accompaniment with the rotation of the jaw cylinder and for causing an operation where the jaw blade moves towards and away from the jaw anvils so as to open and close the jaw mechanism.
This fixed cam is provided with a small diameter section acting in such a manner that the jaw blades come away from the jaw anvils so that the jaw mechanism is put in an open state, and a large diameter section acting in such a manner that the jaw blades come close to the jaw anvils, so that the jaw mechanism is put in a closed state. The fixed cam is of a shape for carrying out straight folding, and specifically the cam shape is such that each jaw mechanism closes and opens once during one rotation of the jaw cylinder.
The following problems are encountered in prior art 1 and prior art 2.
An even number (six) of rows of jaw mechanisms are provided for the jaw cylinder disclosed in prior art 1 so that during collect folding, every other one of the jaw mechanisms are operating in the jaw mechanisms of the jaw cylinder. The six rows of jaw mechanisms can therefore be divided up into three jaw mechanisms that are operating and three jaw mechanisms that are not operating.
The number of times of operation of a bearing for the cam follower coupling with the jaw mechanisms, every other one of which is operating, is high and this bearing therefore wears out very quickly. The generation of noise due to this wearing therefore starts to occur earlier and lifespan is therefore shortened.
An odd number of rows of pins (three) and an odd number of rows (three) of folding blades are provided at the folding cylinder disclosed in prior art 2. During the collect run, the pins and the folding blades of the folding cylinder act in such a manner that every other one of the pins and the folding blades project from the surface of the cylinder. However, the odd number of rows (three) of jaw mechanisms provided on the jaw cylinder facing the folding blade all act so as to open and close in the same way as during a collect run or during a straight run. So-called “paperless strikes” where the jaw mechanism is closed but there is no paper are therefore carried out with respect to every other folding blade that is retracted and held back from the surface of the cylinder.
When the jaw mechanism carries out an empty strike, it is not just the parts that are directly struck such as the jaw blades and jaw anvils making up the jaw mechanism that are affected, but also wearing of the shafts coupling to these parts and the cam follower bearings etc. is speeded up so that the lifespan becomes shorter and noise due to friction is increased.